Chapter 4 of Interpersonal Perception: The Foundation of Social Relationships, as well as Table 5.1 on page 119 and Table 5.2 on page and 123.

The degree to which two perceivers rate a target the same way. Consensus with the is defined within the Social Relations Model as the target variance divided by the total variance. It may seem odd that agreement is indexed by a variance, but if perceivers all exactly agree in their ratings of each target, all of the variance would be due to the targets. Using Laing notation, consensus is symbolized as A(C) = B(C).

Research on consensus addresses a fundamental issue in social science. Social psychologists have looked at consensus to determine if social perception is more in the head of the perceiver than in reality. Personality researchers have used research on consensus to justify the existence of personality traits. Methodologists use consensus to establish inter-rater reliability. Finally, anthropologists use consensus in judging objects (not persons) to validate a common culture.

Consensus is a necessary condition before many other questions in person perception can be asked. Various questions in self-other agreement, target accuracy, and meta-accuracy require consensus.

There is more consensus for extraversion than for the other Big Five factors. However, if perceivers are well acquainted with the targets, there is not much difference in consensus between the the Big Five traits. In general, traits that are more behavioral, external or observable show more consensus.

The level of consensus is fairly modest, ranging from about .20 at zero acquaintance to about .40 at long-term acquaintance. Although longitudinal studies show no increase in consensus as a function of acquaintance, the likely reason is that most the increase occurs very early in the acquaintance process. The PERSON Model can explain why the relationship between acquaintance and consensus is relatively flat. Basically, agreement increases because perceivers better know the target. However, agreement decreases because the effect of shared stereotypes and the effect of agreement about inconsistency decrease. These two effects offset each other to produce essentially a weak relationship between acquaintance and consensus.

Outcome dependence refers to the increased motivation of the perceiver to monitor the target’s behavior. In 1991 Cheryl Flink and Bernadette Park examined the effects of outcome dependence on consensus. They told perceivers “(T)hey would need to select one of the interviewees [i.e., targets] to teach them a task to be performed in the second part of the study” (p. 456). They found that making perceivers dependent on a target did in fact lead to over 25% more relative target variance. These results are consistent with the prior theorizing of Stephen Neuberg and Susan Fiske in 1987 that if a person becomes dependent on a target, that person would then monitor the behavior of the target more closely, which would presumably lead to greater consensus.

For the Big Five, very short-term stabilities after zero acquaintance appear to be very high, approaching perfect stability. Even long-term stabilities over many months have a value of nearly .75. However, the evidence, judgments made at zero acquaintance show much lower levels of stability of .64 and attraction judgments show lower stability.

The average correlation of target effects between two Big Five factors is small, averaging around .10. However, the correlations are larger among Agreeableness, Conscientiousness, and Emotional Stability and between Extraversion and Openness to Experience. Very often the largest correlation is between Agreeableness and Emotional Stability, averaging only .26.

Alexis Geeza, in her 2010 master’s thesis, examined the consensus between different classes of perceivers for each of the Big Five. She studied four different classes of knowledgeable perceivers: roommates, friends, coworkers, and family members. She examined 142 correlations in all. The results showed that an average correlation of target effects between perceivers of two different classes is .73.

The Person Model treats P or Personality, N or Norm times overlap, and S or Stereotype as shared variance leading to consensus. As seen in Figure 4.2 in the 2020 book, consensus starts out at .20 at zero acquaintance, all of which is due to S and asymptotes at .40, all of which is due to P. Note also the change is very abrupt with most of it occurring after just a few acts. The PERSON Model predicts relatively small effect of overlap, q, on consensus. See the shaded area in Figure 4.2, labelled N.

Biesanz, J. C., West, S. G., & Millevoi, A. (2007).  What do you learn about someone over time?  The relationship between length of acquaintance and consensus and self-other agreement in judgments of personality.  Journal of Personality and Social Psychology, 92, 119‑135.

Connelly, B. S., & Ones, D. S.  (2010). An other perspective on personality: Meta‑analytic integration of observers’ accuracy and predictive validity.  Psychological Bulletin, 136, 1092-1122.

Flink, C., & Park, B. (1991). Increasing consensus in trait judgments through outcome dependency. Journal of Experimental Social Psychology, 27, 453-467.

Geeza, A. A. (2010). A meta-analytic examination of consistency in informants’ perspectives across contexts. Master’s Thesis, University of Connecticut.

Kenny, D. A., Albright, L., Malloy, T. E., & Kashy, D. A.  (1994).  Consensus in interpersonal perception:  Acquaintance and the big five.  Psychological Bulletin, 116, 245-258.

Neuberg, S. L., & Fiske, S. T. (1987). Motivational influences on impression formation: Outcome dependency, accuracy-driven attention, and individuating
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